A converging lens of focal length 5 cm is placed at a distance of 20

Mathematics

1 answer:

lesya [120]1 year ago

4 0

The object should be placed 20/cm from the lens so as to form its real image on the screen

<h3>Mirror equation</h3>

The mirror equation is given according to the expression below;

1/f = 1/u + 1/v

where

f is the focal length

u is the object distance

v is the image distance

Given the following parameters

f = 5cm

v = 20cm

Required

object distance u

Substitute

1/5 = 1/u +1/20

1/u = 1/5-1/20
1/u = 3/20

u = 20/3 cm

Hence the object should be placed 20/cm from the lens so as to form its real image on the screen

Learn more on mirror equation here; brainly.com/question/27924393

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Step-by-step explanation:

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Evaluate each finite series for the specified number of terms. 1+2+4+...;n=5

zaharov [31]

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Step-by-step explanation:

The series are given as geometric series because these terms have common ratio and not common difference.

Our common ratio is 2 because:

1*2 = 2

2*2 = 4

The summation formula for geometric series (r ≠ 1) is:

$\displaystyle \large{S_n=\frac{a_1(r^n-1)}{r-1}}$ or $\displaystyle \large{S_n=\frac{a_1(1-r^n)}{1-r}}$

You may use either one of these formulas but I’ll use the first formula.

We are also given that n = 5, meaning we are adding up 5 terms in the series, substitute n = 5 in along with r = 2 and first term = 1.

$\displaystyle \large{S_5=\frac{1(2^5-1)}{2-1}}\\\displaystyle \large{S_5=\frac{2^5-1}{1}}\\\displaystyle \large{S_5=2^5-1}\\\displaystyle \large{S_5=32-1}\\\displaystyle \large{S_5=31}$

Therefore, the solution is 31.

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Summary

If the sequence has common ratio then the sequence or series is classified as geometric sequence/series.

Common Ratio can be found by either multiplying terms with common ratio to get the exact next sequence which can be expressed as $\displaystyle \large{a_{n-1} \cdot r = a_n}$ meaning “previous term times ratio = next term” or you can also get the next term to divide with previous term which can be expressed as: